Occupational whole-body vibration (WBV) exposure can result in back injuries, with females at greater risk. Transmissibility is one way to quantify injury risk; it is measured using accelerometers and defined in the basicentric coordinate system (BCS). The internal axes of accelerometers at the sacrum (S1) and thoracic spine (T6) have been shown to deviate from the BCS dependent on sex, however, the effects on transmissibility are unknown. This work aimed to compare original and corrected transmissibility, and to investigate sex differences at S1 and T6. 17 males and 22 females were exposed to vertical sinusoidal vibration while sitting on a rigid seat with no backrest. Four orthogonal motion capture markers were attached to accelerometers at S1 and T6 to correct acceleration data to the BCS. Transmissibility was calculated using original and corrected accelerations. Differences were examined using a mixed factorial ANOVA. At T6, females had larger (p = 0.031) vertical transmissibility, and sex differences were larger with corrected accelerations. At S1, female vertical transmissibility at resonance was 1.5 times larger (p = 0.007) than males. Cross-axis transmissibility at S1 was larger (p = 0.008) with corrected accelerations. Females experienced greater S1 cross-axis transmissibility at all frequencies, and sex differences were greater with corrected accelerations. Larger cross-axis transmissibility with corrected accelerations suggests that fore-aft spine motion is underestimated when acceleration data aren't corrected, highlighting the importance of accounting for accelerometer orientation. Moreover, despite exposure to the same input vibration, females experienced greater vibration transmission through the spine, which may be associated with higher compressive and shear forces.

Postoperative bronchial fistula and anastomotic stenosis remain significant concerns in lung cancer surgery requiring bronchial reconstruction. Previous studies have shown that basic fibroblast growth factor (bFGF)-induced cartilage regeneration could stabilize anastomosis sites and replace conventional tissue coverage. To inform the optimal configuration of bFGF-based protocols, this study evaluated the relative mechanical effects of varying the number and arrangement of regeneration sites. We developed a mechanically equivalent two-dimensional finite element model based on rabbit tracheal anatomy, with material properties calibrated against quasi-static tensile measurements on whole-trachea component specimens. Stress distributions and principal stress directions were analyzed across configurations of 0, 2, 4, and 8 sites under two loading scenarios: 50% strain (postoperative environment) and 100% strain (surgical upper bound). Across both conditions, as few as two sites were sufficient to eliminate compressive stress at the anastomotic plane, redistribute hydrostatic and principal shear stresses to anchor the cartilage regions, and reduce the angular deviation of the maximum principal stress from the longitudinal axis by approximately 35-36%. Additional sites beyond two showed marginal benefit. The model further predicted that regenerated cartilage progressively suppresses tension-induced anastomotic contraction, with the loaded anastomotic diameter rising from approximately 79% of the cartilage diameter without regeneration to 91% with two sites and 95% with eight sites. While two sites provided sufficient mechanical support in this idealized analysis, the trachea-bronchial system's anatomical complexity suggests a four-point approach warrants further preclinical investigation. These findings provide a mechanical basis for validating cartilage regeneration protocols addressing both anastomotic stability and stenosis prevention.

Virtual articulators require accurate spatial orientation of digital casts for meaningful occlusal analysis during prosthesis design. Current methods for establishing this orientation rely on facial scanning, cone-beam computed tomography, electronic jaw tracking, or arbitrary population-based values. This proof-of-concept technique presents a computational method for determining a functional rotation reference from sequential mandibular intraoral scans captured at controlled opening increments using leaf gauges. The algorithm identifies regions exhibiting minimal translation during jaw opening through systematic grid search within anatomically defined boundaries posterior and superior to the molar positions. Points demonstrating negligible displacement while surrounding structures rotate lie geometrically on or near a rotation axis; a best fit line through their distribution establishes the functional rotation reference. This reference is then transformed to align with the intercondylar axis coordinates of the virtual articulator for digital cast mounting. Forward validation demonstrated root mean square deviations averaging 0.14 mm between simulated and actual scan positions. The technique was implemented for multiple virtual articulator systems including Denar Mark 330, Artex CR, and Stratos 300. This method enables patient-specific virtual articulation using only standard intraoral scanning equipment and leaf gauges, eliminating dependence on supplementary registration hardware.